Low-grade bone lesions in survivors of childhood medulloblastoma/primitive neuroectodermal tumor.

OBJECTIVES AND RATIONALE: Medulloblastoma/primitive neuroectodermal tumor (MB/PNET) is the most common malignant tumor of the central nervous system (CNS) in children. MB/PNET survivors are at an increased risk for developing second malignancies. Little has been reported on development of low-grade lesions of the calvarium in the radiation field in MB/PNET survivors. The purpose of this study was to assess the frequency of the low-grade bone lesion development in the radiotherapy field in pediatric MB/PNET survivors and describe the imaging characteristics of these lesions. MATERIALS AND METHODS: Institutional review board approval was obtained for this retrospective review which was compliant with Health Insurance Portability and Accountability Act. Forty-one MB/PNET patients (29 male) who survived for at least 2 years after initiation of radiation therapy were included. The medical records were reviewed. The most recent available brain magnetic resonance imaging studies were evaluated. RESULTS: Three patients (7.3%) developed low-grade calvarial lesions and underwent resection and/or biopsy of the lesions. There were one Langerhans cell histiocytosis, one benign spindle cell lesion with myxoid change, and one fibrous dysplasia. CONCLUSION: Development of low-grade bone lesions of calvarium is not very rare in pediatric PNET/MB survivors. Bones in the radiation therapy field need to be carefully examined for assessment of secondary lesions.

Teniae coli-based circumferential localization system for CT colonography: feasibility study.

This HIPAA-compliant study, with institutional review board approval and informed patient consent, was conducted to retrospectively develop a teniae coli-based circumferential localization method for guiding virtual colon navigation and colonic polyp registration. Colonic surfaces (n = 72) were depicted at computed tomographic (CT) colonography performed in 36 patients (26 men, 10 women; age range, 47-72 years) in the supine and prone positions. For 70 (97%) colonic surfaces, the tenia omentalis (TO), the most visible of the three teniae coli on a well-distended colonic surface, was manually extracted from the cecum to the descending colon. By virtually dissecting and flattening the colon along the TO, the authors developed a localization system involving 12 grid lines to estimate the circumferential positions of polyps. A sessile polyp would most likely (at 95% confidence level) be found within +/-1.2 grid lines (one grid line equals 1/12 the circumference) with use of the proposed method. By orienting and positioning the virtual cameras with use of the new localization system, synchronized prone and supine navigation was achieved. The teniae coli are extractable landmarks, and the teniae coli-based circumferential localization system helps guide virtual navigation and polyp registration at CT colonography.